New approach to detect seismic surface waves in 1Hz-sampled GPS time series

Recently, co-seismic seismic source characterization based on GPS measurements has been completed in near- and far-field with remarkable results. However, the accuracy of the ground displacement measurement inferred from GPS phase residuals is still depending of the distribution of satellites in the sky. We test here a method, based on the double difference (DD) computations of Line of Sight (LOS), that allows detecting 3D co-seismic ground shaking. The DD method is a quasi-analytically free of most of intrinsic errors affecting GPS measurements. The seismic waves presented in this study produced DD amplitudes 4 and 7 times stronger than the background noise. The method is benchmarked using the GEONET GPS stations recording the Hokkaido Earthquake (2003 September 25th, Mw = 8.3)

Detection of ground motions using high-rate GPS time-series

Monitoring surface deformation in real-time help at planning and protecting infrastructures and populations, manage sensitive production (i.e. SEVESO-type) and mitigate long-term consequences of modifications implemented. We present RT-SHAKE, an algorithm developed to detect ground motions associated with landslides, sub-surface collapses, subsidences, earthquakes or rock falls. RT-SHAKE detects first transient changes in individual GPS time series before investigating for spatial correlation(s) of observations made at neighbouring GPS sites and eventually issue a motion warning. In order to assess our algorithm on fast (seconds to minute), large (from 1cm to meters) and spatially consistent surface motions, we use the 1Hz GEONET GNSS network data of the Tohoku-Oki MW9.0 2011 as a test scenario. We show the delay of detection of seismic wave arrival by GPS records is of ~10 seconds with respect to an identical analysis based on strong-motion data and this time delay depends on the level of the time-variable noise. Nevertheless, based on the analysis of the GPS network noise level and ground motion stochastic model, we show that RT-SHAKE can narrow the range of earthquake magnitude, by setting a lower threshold of detected earthquakes to MW6.5-7, if associated with a real-time automatic earthquake location system

Deformation studies at Furnas and Sete Cidades Volcanoes (São Miguel Island, Azores). Velocities and further investigations

International audienceThe Azores archipelago is located near the triple junction between the Nubian (NU), North America (NA), and Eurasia (EU) plates. It is characterized by a relatively strong seismicity and active volcanism. The best estimate of the current plate velocities in the area over geologic timescales comes from the NUVEL1-NNR model (DeMets et al.) . At the geodetic timescale, plate motion models (Altamimi et al., Sella et al.) including GPS, DORIS, SLR and VLBI data currently do not yet include data from the Azores. In the framework of a research project focused on the seismotectonics and volcanotectonics of São Miguel island, we have analysed GPS data collected there in 1993, 1994, 1997, 2000 and 2002. Our analysis determines both the velocity in the REVEL (Sella et al.) reference frame of São Miguel and its internal deformation. The comparison of the 2000 and 2002 coordinates indicates that São Miguel accommodates moderate WNW-ESE extension at a rate slower than 5 mm yr-1

Present-day deformation in São Jorge Island, Azores, from episodic GPS measurements (2001-2011)

12 pages, 9 figures, 1 tableA network of geodetic markers for high-precision Global Positioning System (GPS) surveying was established in 2001 in the island of São Jorge, at the Azores triple junction, where the North America-Eurasia-Nubia plates meet. The aim was to monitor tectonic, volcanic, and landslide-induced surface deformation in an active tectono-volcanic region. The network consisted of 17 stations, and was occupied in 2001, 2004, and 2010. GPS observations from the three episodic campaigns were analyzed using the latest geophysical models and geodetic procedures to generate a velocity field for São Jorge Island. Surface velocities estimated at 15 inland locations reveal that São Jorge is moving neither with Eurasia nor with Nubia and presents two sectors with different behavior. The NW sector of the island is moving at a rate of 2.2 ± 0.3 mm/yr to N82° ± 6° while the SE sector is moving at a rate of 1.4 ± 0.3 mm/yr to N109° ± 11°, when compared to the velocity of Nubia predicted by ITRF2008-PMM. This velocity field cannot be explained by slip along the active faults that cross the island, nor is compatible with volcanic deformation on the active volcanic rift zones. It is suggested that the velocity differences that are measured represent deformation related to local sub-surficial magmatic/volcanic processes occurring near the island. This intra-island deformation may also be related to the stress field and seafloor spreading occurring in an area situated on the western sector of the Azores Plateau, reflecting the presence of WNW-ESE volcanic structures, along which magma intrusion produces NE-SW dilatation, bounded to the East by a NE-SW trending structure, probably of tectonic nature, working as a dextral transfer zoneThis work was supported by Fundac ão para a Ciência e a Tecnologia (FCT) projects SHA-AZORES (PTDC/CTEGIX/108637/2008), DISPLAZOR (POCTI/1999/CTA/32444), and PEST-OE/CTE/LA0019-2011/2012.We thank the institutions that provided the receivers (IGeoE, IGP, IH, FCTUC, FCUP, and Estereofoto) and all survey participants, in particular Rita Rodrigues, Paulo Amaral, Paulo Sousa, and Gonc alo Prates. We thank Fernando Carrilho, from Instituto de Meteorologia, for providing the seismic catalogue for the 2001-2011 period. We thank Zuheir Altamimi for providing information for the ITRF2008-PMM and Donald Argus for the ITRFVEL- M model. We very much appreciate a thorough review by Donald Argus, which helped much to improve the manuscript. Carefully reviews by Rui Fernandes, an anonymous reviewer, and the Editor are also much appreciatedPeer reviewe

Cuadernos de pedagogía

Resumen tomado de la publicación¿Qué pueden hacer las ONG, las empresas, las entidades vinculadas al deporte, los médicos de familia, los jueces o los municipios? A través de una compilación de aportaciones de varios autores, se hace un recorrido por distintos proyectos que trabajan por la educación desde fuera de la escuela.CataluñaMadrid (Comunidad Autónoma). Servicio de Formación del Profesorado. CRIF Las Acacias; Calle General Ricardos, 179; 28025 Madrid; Tel. +34915250893; Fax +34914660991; [email protected]

Case Law Analysis Regarding High School and Collegiate Liability for Hazing

Hazing has long been a part of group initiation practices within schools, fraternal organizations and sport teams. Recent increases in reported incidents demonstrate that hazing is both prevalent and dangerous within high schools, colleges and universities world-wide. Sport has historically been used to foster a multitude of positive benefits, including teamwork, fair play and physical fitness. Unfortunately, hazing within sport is commonplace and represents a substantial source of liability. The purpose of this study was to conduct a content analysis of US published case law involving liability for hazing at the high school and collegiate levels in order to develop recommendations for educators and sport managers aimed at reducing hazing and limiting liability